Sebastian Software repository standards — agent instructions

You are updating a repository of the sebastian-software GitHub org to match
the org-wide standards defined in this package. Work changelog-driven, prefer
the CLI for mechanics, use judgement only where the changelogs require it.

The model

• Every managed repository carries a .repometa.json:
  { "standards": <version>, "visibility": "oss" | "private", "since": <year>, "exceptions": [...] }
• manifest.json (in this package) defines the current standards version and,
  per scope, which files are managed (byte-exact sync), seeded (created
  once, repos may adapt them) and which README sections (marker-delimited
  blocks) are owned by the standards.
• changes/NNNN-*.md are migration changelogs. Each declares the scopes it
  applies to and describes intent, mechanical steps and judgement calls.
• Scopes are detected from the working tree: common always applies, node
  if package.json exists, rust if Cargo.toml exists (not yet defined).

Workflow

1. Run standards check (CLI of this package; pnpm dlx @sebastian-software/standards check
   in repos that do not have it as a devDependency). If it reports nothing,
   you are done.
2. Run standards apply. It writes managed files, seeds missing ones, updates
   branding sections and bumps the stamp. This covers the mechanical part only.
3. Read every entry in changes/ with a number greater than the repo's
   previous standards stamp, skipping entries whose scope does not apply.
   Carry out their migration steps — this is the part that needs judgement
   (merging configs the repo has customised, removing replaced tooling,
   adjusting package.json scripts).
4. Verify with the repo's own gate: pnpm agent:check if present, otherwise
   lint + format check + typecheck + build + test individually.
5. Open a PR titled chore: standards v<N>. Never push to the default branch.

Rules

• Never reintroduce Prettier. oxfmt is the org formatter. If a repo still
  uses Prettier, migrating away from it is part of the job (see change 0001).
• Seeded files are owned by the repo. Do not overwrite local adaptations —
  merge the intent of the change into them instead.
• Branding sections are owned by the standards. Never hand-edit content
  between <!-- sebastian-software-branding:start/end --> markers; never
  remove the markers. visibility: private repos get the plain copyright
  footer, no marketing.
• Respect exceptions. Entries in .repometa.json#exceptions document
  deliberate deviations (e.g. "keeps-prettier"). Skip the matching steps and
  leave the exceptions in place.
• Do not invent standards. If something is unclear or a reference file is
  missing for the repo's stack, stop and report instead of improvising.